N-acetylcysteine Provides Cytoprotection in Murine Oligodendrocytes through Heme Oxygenase-1 Activity.

Jie Zhou,James C Cloyd,Lisa Basso,Marcia R Terluk,Reena V Kartha,Usha R Mishra,Paul J Orchard,Henning Schröder

doi:10.3390/biomedicines8080240

Abstract

Oligodendrocytic injury by oxidative stress can lead to demyelination, contributing to neurodegeneration. We investigated the mechanisms by which an antioxidant, N-acetylcysteine (NAC), reduces oxidative stress in murine oligodendrocytes. We used normal 158N and mutant 158JP cells with endogenously high reactive oxygen species (ROS) levels. Oxidative stress was induced in 158N cells using hydrogen peroxide (H2O2, 500 μM), and both cells were treated with NAC (50 µM to 500 µM). ROS production, total glutathione (GSH) and cell survival were measured 24 h after treatment. In normal cells, H2O2 treatment resulted in a ~5.5-fold increase in ROS and ~50% cell death. These deleterious effects of oxidative stress were attenuated by NAC, resulting in improved cell survival. Similarly, NAC treatment resulted in decreased ROS levels in 158JP cells. Characterization of mechanisms underlying cytoprotection in both cell lines revealed an increase in GSH levels by NAC, which was partially blocked by an inhibitor of GSH synthesis. Interestingly, we observed heme oxygenase-1 (HO-1), a cytoprotective enzyme, play a critical role in cytoprotection. Inhibition of HO-1 activity abolished the cytoprotective effect of NAC with a corresponding decrease in total antioxidant capacity. Our results indicate that NAC promotes oligodendrocyte survival in oxidative stress-related conditions through multiple pathways.

Highlights

Oxidative stress in the central nervous system (CNS) plays a significant role in the pathophysiology of several neurological conditions [1,2]
There was a lower increase in the extent of cell survival in the presence of BSO when compared to NAC plus H2 O2 group (p < 0.05) and was only 19.4 ± 0.2% when compared to cells treated with only H2 O2. These results demonstrate that inhibition of GSH synthesis following NAC treatment can partly reduce its cytoprotective effects indicating additional mechanisms contributing to NAC benefits
Constitutive high levels of reactive oxygen species (ROS) in mutated glioma cells can be neutralized by a ROS scavenging system dependent on GSH synthesis and metabolism, which can be regenerated by NAC [28]

Summary

Introduction

Oxidative stress in the central nervous system (CNS) plays a significant role in the pathophysiology of several neurological conditions [1,2]. This leads to the accumulation of reactive oxygen species (ROS), which can damage DNA, proteins, and lipids resulting in cell death [3]. Oligodendrocytes, are a type of glial cells are highly vulnerable to oxidative stress. This can disrupt their maturation and cause cell death, an early event in CNS demyelination and neurodegeneration [4]. Reduction in oxidative stress is being explored as an approach for preventing or slowing down the progression of various neurodegenerative diseases [5,6].

Methods

Results

Discussion

Conclusion